Amnesty International has released figures on worldwide use of the death penalty in 2010. The U.S. clocks in at number 5 in terms of the sheer number of executions, ahead of Saudi Arabia and behind Yemen. These are absolute numbers, though, not per capita figures. The BBC has a helpful graph here. Although the article says that the use of the death penalty is continuing to fall, in the sense that the raw number of executions is decreasing, the number of countries that executed people actually went up last year.
Blog of the International Journal of Constitutional Law